The ability to overproduce natural or modified proteins in genetically engineered cells has helped create an expanded biotechnology industry. While some proteins have been expressed in an active state, others have been expressed in an inactive, misfolded configuration. A number of attempts have been made to try to cause a refolding of a protein to an active configuration by adding a chemical. See e.g. J. Cleland, Protein Folding: In Vivo And In Vitro (ACS Series No. 526, Chapter 1) (1993); J. Cleland, et al. 10 Bio/Technology 1013-1019 (1992); C. Schein, 7 Bio/Technology 1141-1147 (1989); J. Cleland, et al., 8 Bio/Technology 1274-1278 (1990); G. Zardeneta et al., 267 J. Biol. Chem. 5811-5816 (1992); and U.S. Pat. No. 4,766,205. The disclosure of these publications and of all other publications referred to herein are incorporated by references as if fully set forth herein. Additives have included chaperone proteins, other types of proteins (e.g. bovine serum albumin), and several types of non-protein materials, including sucrose, glycerol, enzyme substrates (when the protein to be refolded is an enzyme), synthetic polymers, and detergents.
However, for some proteins renaturation of overproduced proteins remains problematic. Therefore, there still is a need to develop strategies for protein refolding that work with proteins resistant to refolding using conventional techniques.